Maximum demand regulator



Nov. 16, 1937. T. s. WINTERS 2,098,986

MAXIMUM DEMAND REGULATOR Filed Dec. 13, 1934 INVENTOR Patented Nov. 16, 1937 UNITED STATES PATENT OFFICE Claims.

This invention relates to an improved method of controlling the maximum load demand imposed upon an electric power circuit.

In general, the purpose of this invention is to regulate the maximum load demand by providing a mechanism which may be attached to an ordinary watthour meter without changing the latter in any way other than the removal of the register.

An object of this invention is to incorporate means in the attachment to the watthour meter for adjusting the maximum demand setting as changing conditions may require.

Another object of this invention is to automatically reduce, and subsequently increase, the load on the power circuit as frequently as may be necessary during any given time interval, so that a set maximum demand will not be exceeded, yet in such a manner that greatest utilization of the permissible demand may be had.

Another object of this invention is to provide a mechanism which does not employ periodic resetting of parts and which does not require synchronization with metering devices used on the same power circuit.

A further object is to eliminate the use of cams and other sliding metal-to-metal surfaces, so that the timing motor will have minimum frictional load.

Another object is to incorporate means in the maximum demand regulator for changing the number of times that the load is decreased and subsequently increased, during any given demand meter interval.

Those skilled in the art will recognize that heretofore there have been employed three general types of devices for controlling maximum demand. The instantaneous type employs a contact-making wattmeter, which has the disadvantage of immediate operation every time that the demand contact setting is reached, without regard to time. This permits objectionable hunting of the load. The integrated type involves the use of contacts actuated by the pointer of a block-interval type of demand meter. When the demand setting of the contacts is reached, it is necessary to disconnect the load which the device controls for the balance of the time interval. Very few users of electric power can tolerate this type of operation because production is usually interrupted. The anticipatory or third type of maximum demand controller employs a block-interval type of demand meter with an additional time mechanism operating a second pointer. When the pointer of the .demand meter comes into register with the pointer of the time mechanism contacts are actuated and the load is reduced. This type has the disadvantage of hunting, employs periodic re-setting and must be synchronized with other demand meters used on the same circuit.

My maximum demand regulator is distinct from the devices described above in that an attachment to a watthour meter is employed, for the purpose intended, in which the load which has been automatically reduced is increased after a load-time integration has been performed. As far as I am aware, my device is the only integrating type of demand regulator that does not require synchronization with other devices used on the same circuit.

The essential features of my invention are hereinafter fully described, are particularly pointed out in the appended claims and are illustrated in the accompanying drawing, in which: Fig. 1 shows the regulator and typical electrical connections thereto. Fig, 2 is an end View of that portion of the regulator designated at A-A of Fig. 1.

Referring to the drawing, the regulator is seen to be provided with a frame 20 to which is attached a cross bar 68. Two bayonet projections, one of which is designated 2|, are integral with the crossbar 68 and provide ready and accurate means for attachment to the watthour meter, which is not shown, save for its disc I, shaft pinion 2, potential coil 62 and current coil 63.

The shaft 1 which is rigidly connected to the differential driven assembly 6, is supported at its two ends in suitable bearings at 66 and 61. Upon the shaft 1 is mounted the first differential driving gear 5, which is rigidly connected to the gear 9 by ahub 65. The second differential driving gear 8 and the gear I I are also mounted on the shaft 1. They are rigidly connected by an integral hub I0. Both gears 5 and 8 are free to turn with respect to the shaft 1. Rigidly connected to the shaft 1 is a clutch disc l2. A contact actuator 14 is supported on the shaft 1 by a hub l5, which is free to turn with respect to the shaft 1. A spring l6 presses against the hub 15 and maintains positive frictional contact between the disc [2, the hub 15 and the interposed friction material l3. The tension of the spring I6 is adjustable by means of the lock nuts 18 on the threaded portion IQ of the shaft 1. Loosely mounted on the shaft I is a washer ll, which is interposed between the spring 16 and the lock nuts [8.

The first differential driving gear 5 is rotated by the watthour meter pinion 2 through the medium of gear 3 and pinion 4.

Meshing with the gear If there is a pinion 39, which is rigidly attached to the horizontal shaft 4|. A driven disc 43 is also rigidly attached to the shaft 4!, which is supported by the micrometer screw and bearing 38, the guide bearing 44 and the combined thrust bearing and co-acting spring 45. The micrometer screw and bearing 38 is provided with a rigidly attached adjusting knob 40. The combined thrust bearing and coacting spring 45 is provided with a pointer 36 which indicates on the scale 56 the axial position of the driven disc 13.

At an angle of degrees with the driven disc 53 there is disposed a driving disc 66, which is connected by a vertical shaft 41 to the gear 43. The shaft fill is supported. by a guide bearing in the frame 28 and the thrust bearing 53. The

thrust bearing 53 is supported by the spring E l, which is attached to the frame 20, so that the driving disc lt makes positive frictional contact with the driven disc $3. The gear 43 is driven by a constant speed motor 52 and the; driving pinion 5| in such a direction that the second differential driving gear a always rotates in a direction opposite to the first differential driving gear 5, which receives its motion from the watthour meter disc 8.

Upon an insulated support 58, which is rigidly fixedto the frame 28, thereare attached two flexible metallic members 23 and 24 upon which are separately mounted the normally closed contacts 22.

A movable arm 28 of insulating material is pivotally attached to the frame ill by the screw 59. Upon the movable arm 28 are mounted two flexible metalliomembers 25 and 271, which carry the normally open contacts 25. The position of the movable arm 28 with respect to the insulated support 58 is indicated by the graduations 55 on the hub of the movable arm 28 and the pointer 29. Thus the contact actuator M is free to travel through the are bounded by the flexible metallic members 23 and 26.

Referring to Fig. 1, it will be seen that a load 66; is supplied from the power line 3d in such a manner that the current flows through the watthour meter current coil 63 and the adjustable shunt 6 3. This load is carried continuously and is not affected by the operation of the regulator. At 6! there is shown another load which is connected to the power line only when the contacts 33 are closed.

The contacts 33 as well as the auxiliary contacts 32 are in the closed position only when the solenoid 3A is energized. This can happen only when the normally open contacts 25 have been closed by the'actuator E4, at which time the solenoidtl is energized by the power line 34. The contacts .32 are connected in parallel with the contacts 25 and in series with the normally closed contacts 22. Thus when the actuator M opens the contacts 22 the solenoid 3! 'is de-energized and the contacts 33 and 32 open, disconnecting the load til from the watthour meter element.

The direction of rotation of the gear 8 which is driven by the constant speed motor 52, is toward the normally open contacts 25, that is, in a clockwise direction as viewed from'A--A. The ear 5' is rotated by the watt hour element in a counter-clockwise direction as viewed from AA. It will be observed that the limit of travel of the actuator M when deflecting in the same direction that gear 5 rotates occurs when the normally closed contacts 22 are separated by the actuator l4 pressing against member 23. This happens when the speed of the gear 5 exceeds that of the gear 8. The solenoid 3| is then ole-energized and the load M is disconnected. As soon as the load 6! is disconnected, the watthour element rotates slower than before, because only the current to load 66 then passes through the current winding t3 and adjustable shunt 3. The reduction in speed of the watthour element then causes the speed of gear 8 to exceed that of gear 5 with the result that the actuator deflects towards the member 26.

The length of are that actuator I4 may travel between the members 23 and 26 is determined by the rotatable arm position as indicated on the graduated scale 55. Thus the setting of the movable arm 28 determines the frequency that the load 6| is connected and disconnected. Since the optimum number of cycles of onoff--on of the loadfil'depends upon the nature of the load 6! as well as the time interval during which maximum demand is measured on the power circuit, it is. desirable to have load-frequency adjusting means. For example, if it is desired to maintain a given maximum demand over a very short interval of time the arm 28 would be adjusted so that the actuator would travel a minimum distance between 23 and 26. Likewise, if a given maximum demand is to be maintained over'a longer time interval the actuator would be allowed a greater are of travel. V

The friction clutch, comprising the parts l2, l3, l5, l6, ll and I8, allows the shaft 7 to turn with respect to the actuator 84 should the latter become unduly restrained, as may happen if the loads; [iii and 6| were entirely disconnected from the circuit by some'external agency and the constant speed motor 52 allow-ed to continue to run. Under certain conditions of restraint the driving and driven discs of the speed changing means may slip suhiciently to make the clutch unnecessary, and I do not purpose to limit the patent in this regard except as provided for in the appended claims.

While I have shown the speed adjusting means positioned on the constant speed side of thedifferential mechanism, it may be more expedient in manufacture to locate the speed adjusting means on the watthour element side of the differential mechanism. a With either location of the speed.- adjusting means, however, so long as the total load corresponds to the proper setting of the speed adjusting means the speeds of the differential gears 5 and 8 are equal and opposite and, no motionis imparted to the contact actuator. Since the watthour element is not used for metering, speed adjustment to suit the maximum load desired may be accomplished by. changing the normal speed of the watthour element, instead of by the friction drive means shown, This may be done by means of an adjustable shunt M, connected in parallel with the watthour element current coil 63.

The regulator may be readily calibrated by passing a known; load through the watthour element while varying the speed adjusting means until the actuator has zero motion when unrestrained. The scale 55 may then be marked in terms of the known value of load.

It is apparent from the foregoing that my maximum demand regulator controls the load on a loadxtime integrated basis. For any particular setting. of the speed adjusting means, with the contacts 32 and 33 closed, an increase in the loads 50 and 6! by external agency shortens the time required for the actuator to open-contacts 22. Likewise, if the contacts 32 and 33 are open and load 8G should be reduced by external agency the actuator would move more rapidly and close contacts 25 and return load 6| to the line faster than it otherwise would. This means that my regulator fills'in the valleys of an electric power curve. as well as it reduces the peaks of the electric power curve. g

Having thus described my invention, what I claim is:

1. In combination with a watthour mete'r, a frame adapted to be readily attached to said watthour meter, a differential gear driven by said watthour meter, a constant speed motor, a driving disc fixed to a vertical shaft and driven by said constant speed motor, a thrust bearing supporting said vertical shaft, a horizontal shaft, a driven disc fixed on said horizontal shaft and free to turn therewith, a spring supporting said thrust bearing and maintaining positive frictional contact between said driving and driven discs, a combined horizontal thrust bearing and micrometer screw, a second horizontal thrust bearing and a spring co-acting therewith, a scale and pointer indicating the axial position of said driven disc, a second differential gear driven by said horizontal shaft in a direction opposite to the first differential gear, a driven differential assembly having pinion engagement with said differential gears, a differential shaft fixed to said differential assembly and supporting freely thereon said differential gears, a friction clutch fixed to said differential shaft, an actuator supported by said differential shaft and co-acting with said friction clutch, normally closed contacts mounted on members of unequal length and disposed so as to be opened by said actuator, a rotatable arm and normally open contacts supported on said rotatable arm and disposed so as to be closed by said actuator.

2. In a maximum demand regulator, a watthour meter, a frame for attachment to said watthour meter, a constant speed motor, a differential mechanism driven in opposing directions by said watthour meter and said constant speed motor, means interposed between said constant speed motor and said differential mechanism whereby the speed ratio thereof may be changed, an actuator responsive to the differential rotations of said watthour meter and said constant speed motor, normally closed contacts mounted on members of unequal length, normally open contacts mounted on other members, means for adjusting the distance between said normally closed contacts and said normally open contacts and a friction clutch for preventing overtravel of said actuator.

3. In a maximum demand regulator, a watthour meter, a frame for attachment to said watthour meter in place of the customary register, a constant speed motor, a differential mechanism driven in opposing directions by said watthour meter and said constant speed motor, means interposed between said constant speed motor and said differential mechanism whereby the speed ratio thereof may be changed, an actuator responsive to the difierential rotations of said watthour meter and said constant speed motor, normally closed contacts mounted upon members of unequal length, normally open contacts mounted upon other members, means for adjusting the distance between said normally closed contacts and said normally open contacts and means for indicating the speed ratio between said constant speed motor and said differential mechanism.

i. In a maximum demand regulator, a watt hour meter element, a constant speed shaft, a. differential mechanism driven in opposing directions by said watthour meter element and said constant speed shaft, an actuator responsive to the differential rotations of said watthour meter element and said constant speed shaft, normally open contacts closable by said actuator and normally closed contacts separable by said actuator.

5. In a maximum demand regulator, 8. watthour element, a constant speed motor, differential gears interposed between said watthour element and said constant speed motor, an actuator responsive to the differential rotations of said watthour element and said constant speed motor, means for maintaining proper speed ratio of said differential gears for different settings of maximum load demand, contact means operable by said actuator for reducing power load, other contact means for increasing power load and a clutch for limiting actuator torque.

6. In a maximum demand regulator, 2. watthour element having speed adjusting means for different values of load, a constant speed motor, differential gears interposed between said watthour element and said constant speed motor, an actuator responsive to the differential rotations of said watthour element and said constant speed motor, contact means operable by said actuator for reducing power load, other contact means for increasing power load and a friction clutch for limiting actuator torque.

7. In a load demand regulating mechanism, a

plurality of gears comprising a differential, means for driving one of said gears at a speed proportional to the load, means for driving another of said gears at a constant speed in the opposite direction, an actuator deriving resultant motion from said differential gears, contact means cooperating with said actuator for alternately reducing and increasing power load and means for adjusting the frequency of oscillation of said actuator.

8. In combination with an electric power line and a watthour meter connected thereto, a noninterrupted load supplied through said watthour meter, an auxiliary load also supplied through said watthour meter, a plurality of gears comprising a differential, means for driving the first of said gears by said watthour meter, means including a constant speed motor for driving another of said gears in a direction opposite to said first gear, an actuator deriving resultant motion from said differential gears, contact means cooperating with said actuator for disconnecting and alternately connecting said auxiliary load and means for changing the cyclic time of travel of said actuator.

9. In a load demand regulating system, an electric power line, a watthour meter connected thereto, a base load connected to said watthour meter, a secondary load, a constant speed motor, differential gears interposed between said watthour meter and said constant speed motor and driven oppositely thereby, an actuator deriving resultant motion from said differential gears, means controlled by said actuator for accomplishing alternate connection and disconnection of said secondary load to said watt-hour meter and means for changing the frequency of connection and disconnection of said secondary load.

10. In a maximum demand regulator, a watthour meter element, a constant speed shaft, a differential mechanism driven in opposing directions by said watthour meter element and said constant speed shaft, an actuator responsive to the differential rotations of said watthour meter element and said constant speed shaft, normally closed contacts separable by said actuator, normally open contacts closable by said actuator and a movable member supporting said normally open contacts.

TED STARLING WINTERS. 

